1 00:00:01,350 --> 00:00:04,470 Hello, everyone, and welcome to this video. 2 00:00:04,710 --> 00:00:09,630 So in this video, we are going to learn about Linux permissions. 3 00:00:09,810 --> 00:00:12,420 Linux permissions are very, very important. 4 00:00:12,420 --> 00:00:21,540 And every one of you should know how these permissions work and how to implement these types of permissions. 5 00:00:21,660 --> 00:00:23,160 So let's quickly begin. 6 00:00:23,400 --> 00:00:33,960 So in Linux, there are three types of permissions that we are going to give to any file or any directories. 7 00:00:34,110 --> 00:00:42,360 Now, these three permissions are the first one is read, which is denoted by a symbol which is R. 8 00:00:42,600 --> 00:00:46,890 The second one is right, which is denoted by W. 9 00:00:47,250 --> 00:00:52,090 And the third one is execute, which is denoted by X. 10 00:00:52,110 --> 00:00:53,850 It is not denoted by E. 11 00:00:53,880 --> 00:00:55,290 It is denoted by X. 12 00:00:55,650 --> 00:01:02,020 So here we know that we have three permissions read, write and execute X. 13 00:01:02,040 --> 00:01:02,700 All right. 14 00:01:02,700 --> 00:01:09,390 So in Linux now, there are three people to whom do we give permissions? 15 00:01:09,720 --> 00:01:12,390 Those are the first one is a user. 16 00:01:12,960 --> 00:01:15,060 The second one is a group. 17 00:01:15,060 --> 00:01:17,130 So user is denoted by you. 18 00:01:17,340 --> 00:01:23,700 The group is denoted by G and others, which is denoted by O. 19 00:01:23,880 --> 00:01:27,660 So a user is someone who has created a file. 20 00:01:27,870 --> 00:01:39,030 The group is for a specific list of users who are in a group and all those people who are not the user, 21 00:01:39,300 --> 00:01:44,340 who have not created the file or the people who are not into a specific group. 22 00:01:44,430 --> 00:01:51,630 For example, let's say there is an organization and all the sales people are already added into a group 23 00:01:51,630 --> 00:01:52,810 which is sales group. 24 00:01:52,830 --> 00:01:59,310 Now those who get added into this group get specific set of permissions. 25 00:01:59,580 --> 00:02:02,160 Those are considered to be a group. 26 00:02:02,790 --> 00:02:04,020 Now, who are others? 27 00:02:04,050 --> 00:02:07,930 Others are who fall out of this category. 28 00:02:07,950 --> 00:02:13,770 They are not into the group, which is the sales group, for example, or those are not the people who 29 00:02:13,770 --> 00:02:16,890 have created the file, which means they are also not the users. 30 00:02:17,340 --> 00:02:20,880 Apart from these people, everyone else is others. 31 00:02:21,360 --> 00:02:24,330 So I hope you guys understood who is others. 32 00:02:24,780 --> 00:02:25,470 Perfect. 33 00:02:25,680 --> 00:02:32,850 So now we need to give permission to these three people user which is denoted by you group which is 34 00:02:32,850 --> 00:02:36,840 denoted by G and others who is denoted by O. 35 00:02:38,840 --> 00:02:39,680 In Linux. 36 00:02:39,680 --> 00:02:46,580 You should know one thing that the permissions are denoted this way for any file or any directory, 37 00:02:46,670 --> 00:02:54,200 which is read, write, execute, hyphen, read, write, execute, hyphen, read, write, execute. 38 00:02:54,440 --> 00:03:03,620 The first block is for the user, the second block is for the group, and the third block is for others. 39 00:03:03,770 --> 00:03:10,730 So this is how the permissions are given to user group and others. 40 00:03:11,820 --> 00:03:20,520 Now in the first block, if it is written as r w x, that automatically means that user has got the 41 00:03:20,520 --> 00:03:25,530 read, write and execute permission, which means the user has all the permissions. 42 00:03:25,560 --> 00:03:33,030 Similarly, the group also have read, write, execute, which means it also has all the permissions. 43 00:03:33,210 --> 00:03:40,020 Similarly, others have RW X, which means it also has all the permissions. 44 00:03:40,020 --> 00:03:40,740 Perfect. 45 00:03:41,040 --> 00:03:50,340 Now let's go to our terminal and let's try to see the permissions for the file, which is X, Y, Z. 46 00:03:50,850 --> 00:03:58,110 Now here the command to see the permission is ls hyphen all through which we are getting the detailed 47 00:03:58,110 --> 00:04:03,060 information of a file which we have created, and the file name is x, y, z. 48 00:04:03,540 --> 00:04:12,630 Here you can notice the permissions that are being given is RW hyphen, ah, hyphen, hyphen, ah, 49 00:04:12,840 --> 00:04:13,830 dash, dash. 50 00:04:13,860 --> 00:04:19,980 Now here you should understand the first block is for user. 51 00:04:20,010 --> 00:04:23,040 The second block is for the group. 52 00:04:23,070 --> 00:04:27,900 Third block is for others, as we have learned until now. 53 00:04:28,020 --> 00:04:34,050 So this automatically means that the user has read and write permission. 54 00:04:34,320 --> 00:04:36,750 The group has read permission. 55 00:04:36,750 --> 00:04:42,750 They cannot write, and others have only and only read permission. 56 00:04:43,630 --> 00:04:43,930 Okay. 57 00:04:43,980 --> 00:04:45,570 So here we know that. 58 00:04:45,570 --> 00:04:47,730 What are the permissions that have been given? 59 00:04:47,760 --> 00:04:51,820 Remember, there is no execute permission given to anyone. 60 00:04:51,840 --> 00:04:53,510 Now what is execute? 61 00:04:53,520 --> 00:04:54,570 You may ask. 62 00:04:54,570 --> 00:05:03,810 So in case there are any scripts that need to be executed then and only then, we need to give them 63 00:05:03,810 --> 00:05:10,450 the permissions of execution or else they will not run or will not get executed. 64 00:05:10,470 --> 00:05:11,160 Perfect. 65 00:05:12,260 --> 00:05:16,220 So let's quickly see the user has the read write permission. 66 00:05:16,220 --> 00:05:20,780 So let's see who is the user currently and the user is root. 67 00:05:20,780 --> 00:05:29,120 And we also know that in the detail of this file, which is X, Y, Z, the user who has created this 68 00:05:29,120 --> 00:05:33,260 file is root and the group is also root perfect. 69 00:05:33,260 --> 00:05:41,030 So now we know that the user is able to read as well as write the file and the user is root itself. 70 00:05:41,270 --> 00:05:49,010 So let's quickly try and see if the user can read it by the command, which is Cat X, Y, Z, and yes, 71 00:05:49,010 --> 00:05:52,460 the user can read the file because the permission is given. 72 00:05:52,610 --> 00:05:58,700 Now let's try if the user can write as well because the permission is given off. 73 00:05:58,700 --> 00:06:03,680 W So let's quickly write into this file using the command nano. 74 00:06:03,680 --> 00:06:09,590 So nano x, y, z and here we can see we are inside the file and we are modifying it. 75 00:06:09,590 --> 00:06:15,320 So let's quickly write something which is this is modified now let's try to save this. 76 00:06:15,320 --> 00:06:22,940 We have saved it and let's try to read it now and see if our changes reflect over there or no. 77 00:06:23,360 --> 00:06:30,260 And here you can see we have successfully modified the file, which means the permissions that are given 78 00:06:30,260 --> 00:06:31,490 are correct. 79 00:06:31,940 --> 00:06:40,820 Now the group has the permission of read, which means anyone who is into the group root can read this 80 00:06:40,880 --> 00:06:49,580 file and let's see the last permission, which is our which is only read, which means others who are 81 00:06:49,580 --> 00:06:56,930 not the user root and who are not into the group root are others. 82 00:06:57,530 --> 00:07:01,100 So let's quickly try to add a user. 83 00:07:01,100 --> 00:07:08,600 So for that we are going to use a command which is user read and let's make a user named Udemy and let's 84 00:07:08,600 --> 00:07:15,500 also give a password for that user, which is Udemy and I have set the password for this user. 85 00:07:15,530 --> 00:07:21,500 Let's quickly switch the user by the command issue and now we have switched the user. 86 00:07:21,500 --> 00:07:23,540 So now we are Udemy. 87 00:07:23,990 --> 00:07:31,730 So let's try to read this file and you have seen through the permission that yes, others get the read 88 00:07:31,730 --> 00:07:32,360 permission. 89 00:07:32,360 --> 00:07:35,600 So that is the reason we are able to read the file. 90 00:07:35,810 --> 00:07:45,410 Now this user is going to try to write the file, which is the W permission and we have seen that the 91 00:07:45,410 --> 00:07:52,610 user does not have the right permission and still he tries to write the file using the command nano. 92 00:07:53,210 --> 00:08:01,280 And here you can see at the first place there is an error which says the file x, y, z is unreadable, 93 00:08:01,280 --> 00:08:08,030 but the user still tries to write and he writes modified by Udemy and tries to save the file. 94 00:08:08,030 --> 00:08:16,820 And it gives an error which is permission denied, which means others, which is the Udemy user, cannot 95 00:08:16,820 --> 00:08:22,250 make changes to file because he does not have the right permissions. 96 00:08:22,640 --> 00:08:28,790 So let's quickly switch back to the main user, which is the root user who has made the file. 97 00:08:28,790 --> 00:08:34,490 And let's see if there are the changes that are being done by the Udemy user or no. 98 00:08:34,490 --> 00:08:42,170 And here we can see there are no changes then, because for obvious reasons Udemy did not have the right 99 00:08:42,170 --> 00:08:48,380 permissions to write into the file X, Y, Z, as we have seen into the permissions. 100 00:08:49,010 --> 00:08:56,060 So I hope you guys understood what are Linux permissions, how it is given and how we have to understand 101 00:08:56,060 --> 00:09:02,060 these permissions in case you have any doubts or queries you can ask into the Q&A section. 102 00:09:02,060 --> 00:09:02,780 Thank you.